Spintronic device and in-memory computing apparatus

Abstract

A spintronic device and an in-memory computing apparatus. The spintronic device comprises: a substrate; and a complex oxide layer and a magnetic tunnel junction structure, which are sequentially formed from bottom to top on the substrate, wherein there is a two-dimensional electron gas region at an interface of the complex oxide layer, and when a read / write voltage is applied to the spintronic device, a spin current generated by the magnetic tunnel junction structure tunnels into the two-dimensional electron gas region at the interface of the complex oxide layer, so as to change the density of a two-dimensional electron gas, such that the magnetic tunnel junction structure completes the reading or writing of data. Therefore, the effect of improving the reading reliability of the device is achieved.

Description

Spintronic devices and in-memory computing devices Technical Field

[0001] This application relates to the field of synaptic technology, and more particularly to a spintronic device and an in-memory computing device. Background Technology

[0002] Spintronic devices are a new type of device that uses electron spin as an information carrier. They exhibit unique advantages in information storage, processing, and transmission, such as non-volatility, high speed, and low power consumption.

[0003] However, spintronic devices are limited by a small switching ratio, which leads to complex external circuit design. Spintronic devices also have the disadvantage of low magnetoresistive ratio, which is not conducive to improving read reliability. Summary of the Invention

[0004] This application provides a spintronic device and an in-memory computing device to improve the high and low resistance magnetoresistance ratio of the spintronic device and enhance the reliability of device readout.

[0005] In a first aspect, embodiments of this application provide a spintronic device, comprising:

[0006] A substrate; and a complex oxide layer and a magnetic tunnel junction structure formed sequentially from bottom to top on the substrate, wherein there is a two-dimensional electron gas region at the interface of the complex oxide layer, and when a read / write voltage is applied to the spintronic device, the spin current generated by the magnetic tunnel junction structure tunnels into the two-dimensional electron gas region at the interface of the complex oxide layer, changing the two-dimensional electron gas density, so that the magnetic tunnel junction structure can complete the reading or writing of data.

[0007] In one possible implementation, a heavy metal layer is further included between the complex oxide layer and the magnetic tunnel junction structure.

[0008] In one possible implementation, the heavy metal layer comprises one or more heavy metals selected from W, Pt, Ta, and Ir.

[0009] In one possible implementation, the magnetic tunnel junction structure comprises, from bottom to top, a magnetic domain free layer, a barrier layer, a reference layer, a pinning layer, and a top electrode.

[0010] In one possible implementation, when a write voltage is applied to the spintronic device, the magnetic domains of the magnetic tunnel junction structure move or contract under the excitation of an electric or magnetic field pulse, causing a change in the relative magnetization ratio of the free layer of the magnetic domains and the reference layer, thereby modulating the resistance of the magnetic tunnel junction.

[0011] In one possible implementation, when a readout voltage is applied to the spintronic device, the spin current generated by the magnetic tunnel junction structure is transformed into a charge current in the two-dimensional electron gas region under the action of spin-charge conversion, forming an electric charge current under the action of a fixed electric field, thereby changing the density of the two-dimensional electron gas.

[0012] In one possible implementation, the charge flow difference generated by different polarization directions of the spin current is fed back into the electric field applied by the spintronic device. The information of the spintronic device and the electric field form a positive feedback relationship, causing a change in the two-dimensional electron gas density. The change in charge density is fed back into the magnitude of the back gate voltage, enhancing the change in the two-dimensional electron gas density.

[0013] In one possible implementation, the complex oxide layer and the magnetic domain free layer are both cuboid structures, and the barrier layer, the reference layer, the pinning layer, and the top electrode are all cylindrical structures.

[0014] In one possible implementation, the complex oxide layer comprises one or more complex oxides.

[0015] In one possible implementation, the complex oxide layer comprises one or more complex oxides.

[0016] Secondly, embodiments of this application provide a spintronic device, wherein the aforementioned spintronic device is the spintronic device described above.

[0017] In one possible implementation, during in-memory weight modulation calculation, the spin orbital moment current of the magnetic storage layer drives the magnetic domains to move, the proportion of the spin direction of the magnetic storage layer changes, and different weights are linearly set.

[0018] During the data reading process in memory, the proportions of different spin directions are between the maximum and minimum charge, exhibiting different conductance values. When a reading voltage is applied, in-memory multiplication and addition operations are realized.

[0019] The spintronic device and in-memory computing device provided in this application embodiment utilize a substrate; and a complex oxide layer and a magnetic tunnel junction structure formed sequentially from bottom to top on the substrate. A two-dimensional electron gas region exists at the interface of the complex oxide layer. When a read / write voltage is applied to the spintronic device, the spin current generated by the magnetic tunnel junction structure tunnels into the two-dimensional electron gas region at the interface of the complex oxide layer, changing the density of the two-dimensional electron gas, thereby enabling the magnetic tunnel junction structure to complete data reading or writing. Therefore, in the solution of this application, the spin synaptic device generates a two-dimensional electron gas at the interface through the complex oxide layer. Through spin current injection, the density of the two-dimensional electron gas is changed under the action of spin-charge conversion. During information writing, different spin polarization directions lead to different changes in the density of the two-dimensional electron gas. During the reading stage, when reading the spin polarization, the change in the density of the two-dimensional electron gas, through feedback from the back gate, improves the high and low resistance magnetoresistance ratio of the spintronic device, thereby improving the reliability of device reading. Attached Figure Description

[0020] The accompanying drawings, which are incorporated herein by reference and constitute a part of the production cost specification, illustrate embodiments consistent with this application and, together with the specification, serve to explain the principles of this application.

[0021] Figure 1 shows the basic structure of the spintronic device provided in this application;

[0022] Figure 2 shows another basic structure of the spintronic device provided in this application;

[0023] Figure 3 illustrates the working principle of the spintronic device provided in this application;

[0024] Figure 4 shows the process of increasing the magnetoresistance ratio of the spintronic device provided in this application;

[0025] Figure 5 shows the electric field-driven writing and reading of multi-resistance state information of the spintronic device provided in this application;

[0026] Figure 6 shows the magnetic domain generation of the spintronic device provided in this application;

[0027] Figure 7 shows the expansion of magnetic domains generated by the spintronic device provided in this application under the drive of a magnetic field;

[0028] Figure 8 shows the fabrication process of the spintronic device provided in this application;

[0029] The accompanying drawings have illustrated specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to specific embodiments. Detailed Implementation

[0030] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0031] Figure 1 is a schematic diagram of the spintronic device provided in this application. As shown in Figure 1, the device includes:

[0032] The substrate; and a complex oxide layer and a magnetic tunnel junction structure formed sequentially from bottom to top on the substrate, wherein there is a two-dimensional electron gas region at the interface of the complex oxide layer. When a read / write voltage is applied to the spintronic device, the spin current generated by the magnetic tunnel junction structure tunnels into the two-dimensional electron gas region at the interface of the complex oxide layer, changing the density of the two-dimensional electron gas, so that the magnetic tunnel junction structure can complete the reading or writing of data.

[0033] In this embodiment, a two-dimensional electron gas (2DEG) is an electronic system formed in a semiconductor heterojunction, in which electrons are confined to a two-dimensional space. This electron gas typically forms at the interface of the heterojunction, where, due to band discontinuities and quantum confinement, electrons are restricted to a two-dimensional region perpendicular to the interface. Within this region, electrons can move freely along the interface plane, exhibiting quantized electronic properties. The two-dimensional electron gas density (electron concentration of the two-dimensional electron gas) refers to the number of electrons per unit area in the two-dimensional electron gas system. A two-dimensional electron gas is a quantum state of electrons, in which the movement of electrons is restricted in one direction, while they can move freely in the other two directions.

[0034] For example, the complex oxide layer is composed of one or more complex oxides, which may include, but are not limited to, La. 1-x Sr x CoO 3-δ Systems such as SrTiO3, LaAlO3 / SrTiO3, BiFeO3 / SrTiO3, or metal oxide / SrTiO3 can form a two-dimensional electron gas at the interface.

[0035] In this embodiment, a two-dimensional electron gas is generated at the interface, allowing the magnetic tunnel junction structure to be injected with a spin flow. The density of the two-dimensional electron gas changes under the influence of spin-charge conversion. During information writing, different spin polarization directions result in different changes in the two-dimensional electron gas density. During the read-out phase, the change in the two-dimensional electron gas density during spin polarization reading, through feedback from the back gate, improves the high-resistivity to low-resistivity ratio of the spintronic device, thereby enhancing the reliability of the device's readout.

[0036] In one example, a heavy metal layer is also included between the complex oxide layer and the magnetic tunnel junction structure.

[0037] It is understandable that the magnetic tunnel junction structure includes a heavy metal interlayer between itself and the two-dimensional electron gas layer to achieve the generation of periodic magnetic domains or magnetic bubbles, while simultaneously generating spin currents with different polarizations. Magnetic domains are spontaneously formed regions within a magnetic material, with each region exhibiting roughly the same magnetization direction. At the macroscopic level, due to the interaction of magnetic domains, magnetic materials can exhibit zero net magnetization. The boundaries of magnetic domains are called domain walls, which are the points where the magnetization direction within the material abruptly changes. The formation of magnetic domains helps reduce the magnetic energy of the material because adjacent domains have opposite magnetization directions, partially offsetting the influence of external magnetic fields.

[0038] In one example, the heavy metal layer includes one or more heavy metals such as W, Pt, Ta, and Ir.

[0039] In one example, the magnetic tunnel junction structure comprises, from bottom to top, a magnetic domain free layer, a barrier layer, a reference layer, a pinning layer, and a top electrode.

[0040] The free magnetic domain layers of the tunnel junction include: one or more of the following: conventional ferromagnetic materials, such as NiFe, CoFeB, Co and CoPt; and one or more of the following: two-dimensional ferromagnetic materials, such as CrBr3, CrTe, FeTe, CrSe, 1T-VSe2, Cr2Ge2Te6, Fe3GeTe2 and Fe5GeTe2.

[0041] A magnetic tunnel junction (MTJ) is a nanostructure consisting of two ferromagnetic layers and a non-magnetic insulating layer. In an MTJ, the magnetization direction of one of the two ferromagnetic layers (the reference layer) is fixed, while the magnetization direction of the other (the free layer) can be reversed by external stimuli (such as a magnetic field or spin-polarized current). The resistance of an MTJ depends on whether the magnetization directions of the two ferromagnetic layers are parallel or antiparallel. This dependence is the basis of the magnetoresistance effect of MTJs and is widely used in spintronic devices such as magnetic random access memory (MRAM).

[0042] It is understandable that this is a heterostructure device based on a tunnel junction structure for storing information and utilizing a two-dimensional electron gas structure within the same device to increase the magnetoresistance ratio. Its principle is shown in Figure 2. Due to spin-orbit coupling, the heavy metal layer generates a longitudinal spin current. At this time, through the auxiliary voltage of the top electrode and the inverse Edelstein effect, the spin current J injected by the ferromagnetic material... S The conversion generates charge current J C , injected into the two-dimensional electron gas region at the interface between the oxide layer and the metal.

[0043] Compared to the approximately 150% high / low magnetoresistance ratio of traditional magnetic tunnel junctions, the working principle of the device in this invention is shown in Figure 3. By changing the ratio of the spin magnetization of the free domain layer to the reference layer, the resistance feedback of the two-dimensional electron gas is altered, and the change in the resistance of the two-dimensional electron gas is fed back to the back gate voltage V. BG Furthermore, by altering the charge density in two-dimensional electrons, the magnetoresistance ratio of magnetic domains can be amplified.

[0044] In one example, when a write voltage is applied to a spintronic device, the magnetic domains of the magnetic tunnel junction structure move or contract under the excitation of an electric or magnetic field pulse, causing a change in the relative magnetization ratio of the free layer and the reference layer of the magnetic domains, thereby modulating the resistance of the magnetic tunnel junction.

[0045] Understandably, the change in the relative magnetization ratio between the free domain layer and the reference layer modulates the magnetic tunnel junction resistance. Due to the dipole and antisymmetric interactions between the heavy metal layer and the free domain layer, the magnetic domains generate a periodic magnetic domain structure as shown on the left side of Figure 6. Different partitions represent different magnetization directions, and the magnetic domains transition along in-plane domain walls through magnetization. The reference layer in the magnetic tunnel junction is magnetized in a fixed direction, such as upward. In this case, the proportion of the magnetization in the boundary region of the free domain layer that is in the same direction as the magnetization of the reference layer reflects the magnitude of the magnetoresistance. If they are exactly the same, it is low resistance; if they are completely opposite, it is high resistance. After being driven by an electric pulse, the domain walls are driven along the current direction and gradually change to the vertical direction, as shown on the right side of Figure 6. Figure 7 shows the expansion of the magnetic domains under the drive of the magnetic field. The above-mentioned magnetic domain change process produces a change in magnetoresistance. However, the magnetoresistance ratio obtained by traditional anisotropic magnetoresistance testing is on the order of 1%, while the magnetoresistance ratio measured using the tunnel junction can reach about 150%. The two-dimensional electron gas change obtained by feedback using the inverse Edelstein effect is beneficial to further increase the high-low resistance ratio through resistance change.

[0046] In one example, when a readout voltage is applied to a spintronic device, the spin current generated by the magnetic tunnel junction structure is transformed into a two-dimensional electron gas region charge current under the action of spin-charge conversion. Under the action of a fixed electric field, an electric charge current is formed, which changes the density of the two-dimensional electron gas.

[0047] Understandably, during the readout process, due to the spin-charge conversion effect, the injection of different polarized spin currents into the two-dimensional electron gas will generate charge currents of different polarities, altering the charge density of the two-dimensional electron gas. This change in charge density is positively correlated with the tunnel junction. The change in charge density is fed back to the back gate voltage, enhancing the change in the two-dimensional electron gas density. This, in turn, increases the high-to-low resistance ratio of the device's lateral resistance. Under the influence of spin-charge conversion, spin polarization is transformed into charge currents within the two-dimensional electron gas region. Under a fixed electric field, this charge current forms, leading to a change in the density of the two-dimensional electron gas.

[0048] As can be understood, as shown in Figure 5, during device readout, a readout voltage is applied to the top electrode. The spin current tunnels through the magnetic layer into the two-dimensional electron gas region. At this time, through the auxiliary voltage of the top electrode and the inverse Edelstein effect, the spin current J injected by the ferromagnetic material... S The conversion generates charge current J C J C The sign of the polarization changes with the direction of ferroelectric polarization. Under the influence of spin-charge conversion, spin polarization is transformed into a charge flow in the two-dimensional electron gas region, leading to a change in the density of the two-dimensional electron gas. Simultaneously, the difference in charge flow generated by different polarizations is fed back to the applied back-gate electric field V. BG In the middle, when the reluctance is low, it has a large electric field V. BG When the magnetoresistance is high, it has a smaller electric field V. BG This creates a positive feedback relationship, further altering the density of the two-dimensional electron gas. This results in a resistance difference far exceeding the magnetoresistance ratio of the spin device itself, thereby increasing the high-low resistance ratio, expanding the readout margin, and improving device reliability.

[0049] In one example, the difference in charge flow generated by different polarization directions of the spin current is fed back into the electric field applied by the spintronic device. The information of the spintronic device and the electric field form a positive feedback relationship, which changes the density of the two-dimensional electron gas. The change in charge density is fed back into the magnitude of the back gate voltage, which enhances the change in the density of the two-dimensional electron gas.

[0050] Understandably, the difference in charge flow resulting from different polarizations is fed back into the electric field applied to the device. When the device information is "0", it has a smaller electric field E1, while when the device information is "1", it has a larger electric field E2, forming a positive feedback relationship and further altering the two-dimensional electron gas density. This generates a resistance difference much higher than the magnetoresistance ratio of the spin device itself, thus improving the high-low resistance ratio of the device. Therefore, during the readout process, magnetization information "0" and magnetization information "1" cause a decrease or increase in the resistance of the two-dimensional electron gas region.

[0051] In one example, the fabrication process of the spintronic device of this application is shown in Figure 8. The fabrication process includes:

[0052] A two-dimensional electron gas basic structure is formed by growing a bottom electrode and a complex oxide layer on a silicon, silicon oxide or SrTiO3 substrate using a laser pulse deposition method.

[0053] The junction region is etched using ion beam etching technology, and the bottom electrode and the upper two-dimensional electron gas are isolated by SiO2.

[0054] A heavy metal layer, a magnetic domain free layer, a barrier layer, a reference layer, a pinning layer, and a top electrode are grown on the upper layer of the material using magnetron sputtering.

[0055] The cylindrical magnetic tunnel junction (MTJ) structure was patterned and etched using photolithography and ion beam etching techniques.

[0056] Etch the heavy metal layer and the top electrode pattern area. Fabricate the complete device.

[0057] The in-memory computing device provided in this application includes the aforementioned spintronic device.

[0058] In-Memory Computing (IMC) is a computing paradigm that tightly integrates data processing and storage, aiming to solve the "memory wall" problem in traditional von Neumann architectures. In traditional architectures, the processor and memory are separate, and data needs to be transferred back and forth between them, leading to significant performance bottlenecks. In-Memory Computing reduces the number of data moves by performing computations directly in the storage device, thereby reducing energy consumption and latency, and improving system efficiency and responsiveness. In-Memory Computing technologies typically utilize specific storage devices that can not only store data but also perform simple computational operations such as addition, multiplication, or comparison.

[0059] Spintronic devices can be found in the above-described method embodiments, and their implementation principles and technical effects are similar, so they will not be described again here.

[0060] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0061] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0062] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0063] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0064] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0065] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0066] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0067] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0068] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0069] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0070] If the functionality is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0071] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0072] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A spintronic device, characterized in that, include: Substrate; Furthermore, a complex oxide layer and a magnetic tunnel junction structure are sequentially formed from bottom to top on the substrate, wherein there is a two-dimensional electron gas region at the interface of the complex oxide layer. When a read / write voltage is applied to the spintronic device, the spin current generated by the magnetic tunnel junction structure tunnels into the two-dimensional electron gas region at the interface of the complex oxide layer, changing the two-dimensional electron gas density, thereby enabling the magnetic tunnel junction structure to complete the reading or writing of data.

2. The spintronic device as described in claim 1, characterized in that, A heavy metal layer is also included between the complex oxide layer and the magnetic tunnel junction structure.

3. The spintronic device as described in claim 1, characterized in that, The heavy metal layer includes one or more heavy metals selected from W, Pt, Ta, and Ir.

4. The spintronic device as described in claim 1, characterized in that, The magnetic tunnel structure comprises, from bottom to top, a magnetic domain free layer, a barrier layer, a reference layer, a pinning layer, and a top electrode.

5. The spintronic device as described in claim 4, characterized in that, When a write voltage is applied to the spintronic device, the magnetic domains of the magnetic tunnel junction structure move or contract under the excitation of an electric or magnetic field pulse, causing a change in the relative magnetization ratio of the free layer of the magnetic domains and the reference layer, thereby modulating the resistance of the magnetic tunnel junction.

6. The spintronic device as described in claim 4, characterized in that, When a readout voltage is applied to the spintronic device, the spin current generated by the magnetic tunnel junction structure is transformed into a charge current in the two-dimensional electron gas region under the action of spin-charge conversion, forming an electric charge current under the action of a fixed electric field, thereby changing the density of the two-dimensional electron gas.

7. The spintronic device as described in claim 6, characterized in that, The charge flow differences generated by the different polarization directions of the spin current are fed back into the electric field applied by the spintronic device. The information of the spintronic device and the electric field form a positive feedback relationship, which changes the two-dimensional electron gas density. The change in charge density is fed back into the magnitude of the back gate voltage, enhancing the change in the two-dimensional electron gas density.

8. The spintronic device as described in claim 4, characterized in that, The complex oxide layer and the magnetic domain free layer are both cuboid structures, while the barrier layer, the reference layer, the pinning layer, and the top electrode are all cylindrical structures.

9. The spintronic device as claimed in claim 1, characterized in that, The complex oxide layer includes one or more complex oxides.

10. An in-memory computing device, characterized in that, Includes the spintronic device as described in any one of claims 1 to 9.

Images